1. Field of the Invention
The present invention relates to removable orthodontic appliances that exert corrective forces on teeth.
2. Description of the Prior Art
Orthodontics is a specialty of dentistry which is concerned with the treatment of malpositioned teeth and the correction of improper relationships of the teeth and dental arches. It is common to utilize extra-oral orthodontic appliances to correct improperly positioned teeth. It is also common in extra-oral appliances to use some form of elastic mechanism so that a force can be applied to the teeth.
Headgear assemblies are commonly used in orthodontic treatment to apply forces to a patient's teeth to accomplish specific types of tooth movements. Such headgear assemblies typically include an inner bow, an outer bow and some type of a neck/head strap assembly. More particularly, the two ends of the inner bow are each typically inserted into a buccal tube attached to one of the upper first molars. Moreover, the outer bow is connected to the inner bow and extends at least partially about both sides of the patient's face such that the ends of the outer bow may be engaged by the neck/head strap assembly. The neck/head strap assembly is generally formed at least in part from an elastic material or other energy-storing mechanism so as to be capable of stretching and, thus, applying the desired treatment forces to each of the ends of the outer bow. These treatment forces are then typically transmitted to the upper first molars and any teeth interconnected therewith (e.g., via an arch wire and/or other appropriate connectors).
The most common type of force producing device is the coil spring. Coil springs that have been commonly used in the past are stainless steel springs. The advantage of springs as a force producing device is that they almost never require replacement during the entire length of time of usage. The disadvantage of most springs that are in common use is that they do not apply a constant force over different deflections. Deflection increases and decreases when the user speaks or moves his or her head. Therefore, when using the conventional stainless steel type of spring, the force that is applied is constantly changing. Orthodontists feel that constant force application moves the teeth more efficiently than variable forces. Furthermore, variable forces can cause pain, especially if the force significantly increases momentarily.
Moreover, to be effective, an orthodontic device must be worn over an extended period of time each day. In addition, orthodontists, in many cases, guarantee that they will be able to align a patient's teeth. For both purposes, it is desirable to record how long a patient actually wears an orthodontic device and the amount of extra-oral force exerted.
The use of removable appliances that exert corrective forces on teeth such as headgears, mono-blocks, activators, crozats, retainers, spring-loaded retainers and the like is at the discretion of the patient who most often is an adolescent. Since the appliance may be somewhat uncomfortable and inconvenient to wear, it takes considerable will power to adhere to a treatment program. It can be particularly difficult to adhere to a program for an adolescent who may not fully recognize the true value of the treatment.
The rate of corrective movement of teeth is a function both of the forces applied to the teeth and the amount of time those forces have been applied. Failure to wear an appliance for the prescribed periods results in reduced corrective movement of the teeth and, in addition, such failure can result in the use of incorrect forces in later stages of the treatment. As treatment progresses, forces are often determined in relation to the effectiveness of forces used in earlier stages. If a patient represents that the program has been fully complied with when, in fact, it has not, the orthodontist is led to believe that the forces applied earlier were insufficient to cause the desired rate of tooth movement. As a consequence, excessive forces may later be chosen which can work to the detriment of the patient.
It is an object of the present invention to provide an orthodontic care device capable of applying an extra-oral force to a patient's jaw/teeth and of recording the force applied thereto as a function of the amount of time the device is actually worn.
Another object of the invention is to provide a memory read-out unit capable of reading the force/time history recorded by said orthodontic care device and storing such history, possibly with other previously stored force/time histories, for future retrieval.
An additional object of the invention is to provide means, such as a serial or parallel port, for down-loading information stored in the memory read-out unit into a computer so that the information can be analyzed, utilizing a suitable computer program, and printed out in a convenient format for review by an orthodontist and his patients.